1. Field
One or more embodiments of the present invention relate to an apparatus and method for generating a three-dimensional map, and, more particularly, to an apparatus and method for generating a three-dimensional map using structured light that is emitted upward to a ceiling.
2. Description of the Related Art
In general, robots have been developed to improve factory automation. In recent years, robots available for home and office use as well as industrial robots have been put to practical use. Examples of the robots available for home and office use include cleaning robots, guide robots, and security robots.
In mobile robots, such as cleaning robots, it is generally indispensable to create a map that is recognized by the robots in order to designate a traveling path of the robot or a working area of the robot. In order to create the map, various methods, such as methods of using a vision sensor, an ultrasonic sensor, and a touch sensor, have been used to control the robot to create a map while being autonomously navigated. However, a method of using structured light and a camera is very effective since it needs a small amount of computation and can be used in a place where there is a large variation in brightness.
In this method, as shown in FIG. 1, an active light source 10, such as a laser, is used to emit a predetermined laser beam to an obstacle 30, and a sensor 20, such as a camera, captures an image formed by the laser beam reflected from the obstacle. Then, it is possible to calculate the distance between the laser emission point and the obstacle 30, which is a reflection point, by using a triangular method, on the basis of coordinates of the image captured by the camera 20, the radiation angle of light, and the distance between the camera 20 and the laser emission point.
In the related art, since light is emitted in the forward direction in which the mobile robot moves, the mobile robot can generate only a two-dimensional map due to limited information.
In FIG. 1, a distance d between the light source 10 and the camera sensor 20 is referred to as a baseline. The longer the distance becomes, the higher the range resolution becomes. When robots having a limited height, such as cleaning robots, emit light forward, in many cases, the baseline is short. In this case, the range resolution at a long distance is lowered, which makes it difficult to generate a map.